REDUCTION OF SACCHAROMYCES CEREVISIAE, ESCHERICHIA COLI AND LISTERIA INNOCUA IN APPLE JUICE BY ULTRAVIOLET LIGHT

Abstract

Apple juice was inoculated separately with Saccharomyces cerevisiae, Listeria innocua (ATCC 51742) or Escherichia coli (ATCC 11775) for treatment in a double tube ultraviolet (UV) disinfection system. The apple juice was treated at six flow rates (0.073–0.548 L/min) for selected fluences (75–450 kJ/m2). The juice was also inoculated with a mixture of these three microorganisms and UV light treated from 0.548 to 0.735 L/min for 30 min. The microbial reduction was described with a first order kinetic model. Average Duvvalues of 23.1–40.5, 8.2–20.6 and 6.0–17.7 min were obtained for S. cerevisiae, L. innocua and E. coli, respectively. A linear model was used to describe the relationship between log Duvversus flow rate for S. cerevisiae and L. innocua. However, a third order polynomial model was more adequate for describing the E. coli Duvvalues versus flow rate. Less than 10 (no growth), 190 and 200 cfu/mL of S. cerevisiae, L. inocua and E. coli, respectively, were observed in UV‐treated apple juice inoculated with a mixture of microorganisms.

Fundamental Characteristics of Deep-UV Light-Emitting Diodes and Their Application To Control Foodborne Pathogens

“…This added resistance may be due to the thick peptidoglycan wall that surrounds the cytoplasmic membrane in Gram-positive bacteria, whereas Gram-negative bacteria possess only an external membrane (26). Many research studies investigating the sanitization of foodborne pathogens in various foods report that L. monocytogenes is considered to be one of the most UV-resistant bacteria (27,28,29).…”

Efficacy of Ultraviolet Radiation as Non-thermal Treatment for the Inactivation of Salmonella Typhimurium TISTR 292 in Pineapple Fruit Juice

“…The increase of frequency gave lower residence time for the pineapple juice inside the tube (Table 1). This showed that the residence time decreases as the flow rate increases, thus, giving a less probability of exposure time of the juice to the UV-C light (Guerrero-Beltran and Barbosa-Canovas, 2005). The Dean number of the reactor also had an increasing pattern with 77, 100 and 119 for flow rates of 0.0078, 0.1022 and 0.1210 l/min, respectively.…”

Ultraviolet-C Light Effect on Pitaya (Stenocereus griseus) Juice

“…D uv values decreased as flow rates increased, this means that the inactivation of the microbial load increased as flow rate increased. Guerrero-Beltrán & Barbosa-Cánovas (2005) reported D uv values of 5.9, 7.0, and 22.4 minutes for E. coli, L. innocua, and S. cerevisiae inactivation in apple juice treated with UV-C light at a flow rate of 9.13 mL/s. Torkamani & Niakosari (2011), on the other hand, reported D uv values of 0.82 and 1.05 kJ/m 2 for total counts and yeasts plus molds, respectively, in not inoculated orange juice.…”

“…Pitaya juice possesses a dark red-purple color and this could avoid the penetration of light; however, turbulence regime, formed by increasing the speed, is enough for making all the liquid be in contact with the UV-C light and obtain a greater microbial inactivation (Li, Deng & Nyung, 2010). Caminiti et al (2010) and Guerrero-Beltrán & Barbosa-Cánovas (2005) pointed out that the transparency and soluble and insoluble solids of the liquid food product, or medium, are critical factors in the microbial inactivation with UV-C light; both color and turbidity may block the pathway of light and prevent to microorganisms to be reached by the UV-C light. Li et al (2010) reported that the penetration of UV-C light in the product is of utmost importance since better results, regarding microbial inactivation, are obtained on the surface of the food.…”

“…The UV-C lighth as recently been used for researching in the fruit juices processing area, but this has been mainly focused on the inactivation of microorganisms (Guerrero-Beltrán & Barbosa-Cánovas, 2005;Gabriel & Nakano, 2009;Lu et al, 2010), enzymes (Barkaet al, 2000;Guerrero-Beltrán & Barbosa-Cánovas, 2006), and changes in color (Keyser et al, 2008). Few researchers have comprehensively assessed the UV-C lighte ffects (Pala & Tocluku, 2010;Falguera et al, 2011) on other fruit juice components.…”